1. Technical Field
The present invention relates in general to power distribution within an integrated circuit (IC) chip, and in particular to an apparatus and method for improving DC distribution efficiency for IC applications. More particularly, the present invention relates to an on-chip, multi-plane voltage distribution system that incorporates a self-regulating voltage divider for efficiently scaling external power boundaries.
2. Description of the Related Art
With switching thresholds in the tenths of a volt region for sub-micron IC devices, the trend in power supply technology is toward lower supply voltage levels. In addition to reducing power consumption, operation at lower voltages also reduces electric field across internal device nodes, resulting in more reliable operation of devices having sub-micron physical dimensions. To achieve such benefits, application board supply voltages as low as 1.2 volts DC are becoming commonplace. While reducing on-chip power consumption, however, such low supply voltages are achieved at a substantial cost in power supply overhead hardware that is required for additional DC-to-DC conversion stages. In addition, the electrical efficiency of low output voltage power supplies suffers due to the power consumption of the regulation and DC-to-DC conversion circuitry.
Most power supplies are required to support a variety of data processing system requirements in addition to those of internal microcircuits. For a personal computer, such additional requirements may include, for example, the power supply fan, magnetic and optical disk drivers, and input/output (I/O) bus support. Power supplies for larger scale data processing systems may be required to support multiple disk arrays, telecommunication infrastructure, and the like. The vast disparity between the voltage levels required for these applications and the IC chip voltage levels further increases power supply overhead hardware requirements and reduces power supply efficiency.
AC source power supplies operate more efficiently at higher voltages as both a consequence of having fewer voltage level conversion stages and lower current losses. For batteries, fundamental physical reactions typically result in output voltages in the range of 1V to 3V based on chemical compositions.
To meet disparate power supply requirements from applications that demand high power density, low power consumption, and high efficiency, power supplies for high-level data processing systems, such as network servers, must often be custom designed. Significant development time and resources are required to support such customization for systems having individualized power requirements. Since the design and construction of a custom power supply presumably overlaps the design phase of the data processing system, supply capacity requirements may have to be adjusted, resulting in an overall delay in product development.
From the foregoing, it can be appreciated that a need exists for an on-chip DC power distribution system that will provide relief for the low-voltage conversion requirements of multi-purpose power supplies.
A system and method for achieving self-regulated voltage division among multiple serially stacked voltage planes are disclosed herein. The system of the present invention is incorporated within a source voltage plane having a source supply node for supplying power and a source ground node for sinking current supplied therefrom. An intermediate voltage supply node is coupled between the source supply voltage node and the source ground node for dividing the source voltage plane into a plurality of intermediate voltage planes. The self-regulated voltage divider of the present invention includes a first capacitor and a second capacitor that are each controllably coupled between either the source supply voltage node and the intermediate voltage supply node, or between the intermediate voltage supply node and the source ground node, such that a voltage level balance is achieved among the intermediate voltage planes.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.